Estimates are that for every $1 spent on preventative pavement maintenance, between $4 and $10 are saved on rehabilitation. This illustrates why, in today’s fiscally constrained environment, investment in maintenance and preservation is crucial. This project evaluated WSDOT’s current process for calculating pavement improvement benefits and then developed an improved approach for measuring the benefits of those highway preservation projects.
To quantify the regional economic benefits associated with its transportation investment projects, WSDOT currently combines investment costs associated with highway project improvements with user and maintenance costs derived from software developed by the Federal Highway Administration known as the Highway Economic Requirements System—State Version (HERS-ST). The focus of the FHWA software is primarily projects such as new road construction, but highway preservation and maintenance may also be included.
To better understand how other state transportation departments evaluate different improvement alternatives and to gauge to what extent they utilize the HERS-ST software, the researchers conducted a comprehensive national survey of state DOTs. The survey results revealed that only four states still utilize the HERS-ST software, and they vary widely in the ways they evaluate pavement projects.
The researchers developed a tool to supplement the HERS-ST for benefit and cost estimation processes. The Excel-based HERS-ST Benefit Application Tool (HERS-ST-BAT) improves the existing process by allowing users to include reconstruction and overlay scenarios in asphalt and concrete pavement models, to add user costs to compare improved and unimproved pavements over five-year periods, and to input customizable values rather than national averages for data such as fuel costs, taxes, and travel times.
The researchers applied the HERS-ST-BAT to three previous WSDOT highway projects. Measurable user costs and maintenance costs were estimated and applied to different scenarios. In comparison to scenarios without any improvement, the scenarios with improvements at the appropriate time showed reductions in total costs of 0.25 percent to 1.09 percent at the county level. Results showed that the more that specific improvements are delayed, the less total cost savings an agency will realize.
The new method, combining the HERS-ST-BAT tool with HERS-ST, is applicable to various pavement improvement projects, can be used by regional transportation agencies, especially those without a statewide travel demand model, and has the potential to increase consistency across states. With the new tool, states can time maintenance and preservation projects to maximize long-term benefits to road users, regional economies, and the highway system—and make more strategic choices with current budgets.
Authors:
Eric L. Jessup
You Zhou
Eric Lang
WSU Freight Policy Institute. School of Economic Sciences
Sponsor: WSDOT
WSDOT Technical Monitor: Wenjuan Zhao
WSDOT Project Manager: Doug Brodin